Housing unit for an electric machine

ABSTRACT

A housing includes a first housing unit which includes a first bearing shield, a flange, a stator laminated core arranged between the first bearing shield and the flange, and a coating which is made of stainless steel and applied by an additive manufacturing method so as to cover the first bearing shield, the stator laminated core, and the flange and thereby form a unitary structure.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the priority of European Patent Application,Serial No. 17160139.6, filed Mar. 9, 2017, pursuant to 35 U.S.C.119(a)-(d), the disclosure of which is incorporated herein by referencein its entirety as if fully set forth herein.

BACKGROUND OF THE INVENTION

The present invention relates to a housing unit for an electric machine,in particular a PM (permanent magnet) servomotor.

The following discussion of related art is provided to assist the readerin understanding the advantages of the invention, and is not to beconstrued as an admission that this related art is prior art to thisinvention.

Housing units of this type are used for PM servomotors, for instance.With special applications, there is a requirement that the housing ofthe electric machine should or must be made of stainless steel.Stainless steel housings of this type have the negative characteristicthat they exhibit a poor heat discharge, so that the permissible powerof the electric machine, in most case the motor, has to be reducedaccordingly or the motor has to be designed accordingly larger thancomparable motors without stainless steel housings.

It would therefore be desirable and advantageous to provide an improveda thin-walled stainless steel housing for an electric machine to obviateprior art shortcomings in a cost-effective and simple manner.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a housing includes afirst housing unit including a first bearing shield, a flange, a statorlaminated core arranged between the first bearing shield and the flange,and a coating made of stainless steel and applied by an additivemanufacturing method so as to cover the first bearing shield, the statorlaminated core, and the flange and thereby form a unitary structure.

According to another aspect of the present invention, an electricmachine including a first housing unit including a first bearing shield,a flange, a stator laminated core arranged between the first bearingshield and the flange, and a coating made of stainless steel and appliedby an additive manufacturing method so as to cover the first bearingshield, the stator laminated core, and the flange and thereby form aunitary housing structure.

The present invention resolves prior art problems by manufacturing ahousing or housing unit for the electric machine not completely fromstainless steel, but merely to coat the outer housing layer withstainless steel. This stainless steel coating is carried out by means ofan additive manufacturing method, for instance using the MPA (metalpowder application) technique. To this end stainless steel particles inthe metal adhesive bond are bonded, in effect welded, to the housingunit. Here the first bearing shield, the stator laminated core and theflange are provided with a shared stainless steel coating as thesmallest unit for the housing. Therefore both the first bearing shield,generally the AS (drive-side) bearing shield, and similarly the flangecan be made from raw material such as aluminum or ferrous metal, Duringmanufacture, the stator lamination, which is also frequently referred toas the yoke package, is joined to the bearing shield and the flange in afirst step and a stainless steel coating is then applied thinly, forinstance approx. 1 to 3 mm. This results in a metallic adhesive bondwith a low-thickness stainless steel layer, which has the sameadvantages as a complete stainless steel housing part, however, and atthe same time ensures a significantly improved heat dissipation. Onaccount of the stainless steel coating, sealing elements and screws fora material bond can be conserved; similarly with the thin-walled coatingwith stainless steel, this relatively expensive stainless steel materialcan be used sparingly which results in a cost saving.

According to another advantageous feature of the present invention, thecoating includes stainless steel particles to establish a metal adhesivebond with the first bearing shield, the flange, and the stator laminatedcore. The coating in the additive manufacturing method also ensures ametallic adhesive bond even with highest bonding forces. Moreover, theadditive manufacturing method gives rise to very high flexibility inrespect of installation length and diameter for the housing unit or forthe electric machine.

A suitable method for stainless steel-coating the housing unit involvesan additive manufacturing method, e.g. what is known as the MPA (metalpowder application) technique. Here the stainless steel coating of thehousing unit is generated easily by stainless steel particles in themetal adhesive bond being bonded to the first bearing shield, the flangeand the stator laminated core.

According to another advantageous feature of the present invention, thefirst housing unit can be configured to receive a rotor laminated corehaving magnets arranged thereon and interacting with a shaft made fromstainless steel and supported in bearings. In this way a simple assemblyof the housing unit to form a complete electric machine can be ensured,with the rotor laminated core embodied to interact with a rotormanufactured in particular from stainless steel.

According to another advantageous feature of the present invention, asecond housing unit can be provided which includes a bearing shield anda coating made of stainless steel and applied by the additivemanufacturing method so as to cover the bearing shield of the secondhousing unit, with the first housing unit being configured to connect tothe second housing unit. Thus, a complete housing of a stainlesssteel-coated electric machine can be produced easily in that the housingunit is provided for coupling with a second bearing shield coated with asecond stainless steel coating.

According to another advantageous feature of the present invention, atleast one of the coating of the first housing unit and the coating ofthe second housing unit can have a region configured to include acooling duct to establish a heat discharge, with the cooling duct beingproduced by the additive manufacturing method. In this way, the additivemanufacturing method can be used to selectively provide the housing unitwith in particular thin-walled and filigree cooling ducts for furtherimprovement of the heat discharge.

In accordance with the present invention, a complete electric machinecan be easily created in that the electric machine has a rotor unitcomprised of a rotor, rotor laminated core, magnets and bearings.

A complete stainless steel housing for an electric machine is ensured inthat the electric machine has a stainless steel housing formed from thehousing unit and from the second bearing shield.

According to still another aspect of the present invention, a method forproducing an electric machine includes joining in a first manufacturingstep a first bearing shield, an outer laminated core, and a flange; andcoating by using an additive manufacturing method the first bearingshield, the outer laminated core, and the flange with a coating made ofstainless steel such that stainless steel particles in the coating forma metal adhesive bond with the first bearing shield, the flange, and theouter laminated core to establish a first unitary housing structure.

According to another advantageous feature of the present invention, awound stator laminated core can be inserted in a third manufacturingstep into the unitary housing structure.

According to another advantageous feature of the present invention, arotor unit comprised of a shaft, bearings, a rotor laminated core andmagnets can be inserted in a fourth manufacturing step into the housingstructure to produce a motor unit.

According to another advantageous feature of the present invention, asecond bearing shield can be fastened in a fifth manufacturing step tothe motor unit so as to complete the production method for the electricmachine.

The finished electric machine can be optimized smoothing the housingunit and/or the motor unit by a metal-cutting process and/or by anelectropolishing method.

BRIEF DESCRIPTION OF THE DRAWING

Other features and advantages of the present invention will be morereadily apparent upon reading the following description of currentlypreferred exemplified embodiments of the invention with reference to theaccompanying drawing, in which:

FIG. 1 shows a sectional view of an electric machine with a housing witha stainless steel coating in accordance with the present invention,

FIG. 2 shows a sectional view of basic components of the electricmachine, as preparation for a housing unit of the electric machine,

FIG. 3 shows a sectional view of a housing unit with stainless steelcoating and a wound star-shaped laminated core, and

FIG. 4 shows an assembled housing unit as a stator unit and associatedrotor unit.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Throughout all the figures, same or corresponding elements may generallybe indicated by same reference numerals. These depicted embodiments areto be understood as illustrative of the invention and not as limiting inany way. It should also be understood that the figures are notnecessarily to scale and that the embodiments may be illustrated bygraphic symbols, phantom lines, diagrammatic representations andfragmentary views. In certain instances, details which are not necessaryfor an understanding of the present invention or which render otherdetails difficult to perceive may have been omitted.

Turning now to the drawing, and in particular to FIG. 1, there is showna sectional view of an electric machine, generally designated byreference numeral 1 and including a housing provided with stainlesssteel coatings 16, 17. The electric machine 1 essentially includes twohousing units. The main housing unit, the production method for which isexplained in detail in conjunction with FIGS. 2 to 4, essentiallyincludes a first bearing shield 10, a stator laminated core 3 and aintermediate flange 12. This housing unit thus forms a stator unithaving a shared stainless steel coating in the form of the firststainless steel coating 16. The second housing unit essentially includesa second bearing shield 11, which likewise has a second stainless steelcoating 17. The special feature of the housing or electric machine 1shown in FIG. 1 is that the entire housing has a stainless steel coating16, 17, which is generated by means of an additive manufacturing method.These stainless steel coatings 16, 17 can be applied thinly, forinstance with a thickness of 1 to 3 mm. As a result of the metallicadhesive bond between the stainless steel coating and the underlyingaluminum or ferrous metal or the electrical sheet of the statorlaminated core 3, heat dissipation of the housing and the electricmachine 1 is significantly improved compared with a complete housingmade from stainless steel. Furthermore, material can be saved by meansof the thin-walled coating using stainless steel. The coating in theadditive manufacturing method ensures a metallic adhesive bond withhighest bonding forces.

The further components of the electric machine 1 shown in FIG. 1 are ofessentially of a conventional type. For example, the electric machine 1has a wound star-shaped laminated core 4. Furthermore, bearings 6 areprovided for mounting the rotor unit 15 assigned to the shaft 8, therotor laminated core and the magnets 7.

FIG. 2 shows a section through basic components of the electric machine1 shown in FIG. 1. These basic components involve a bearing shield 10,an intermediate flange 12, a stator laminated core 3 and a bearingshield. These are joined together in a first manufacturing step 20 inthe manner shown in FIG. 2. Here the first bearing shield and the flange12 generally are made of aluminum or ferrous metal, while the statorlaminated core is composed of electrical sheet.

FIG. 3 shows a section through a housing unit 5 with stainless steelcoating 16 and a star-shaped laminated core 4 which, during a thirdmanufacturing step 22, is inserted into the housing unit 5 of thestar-shaped package. With the method according to the invention, thesecond manufacturing step 21 involves application of a shared stainlesssteel coating upon the basic components comprised of first bearingshield, flange and stator laminated core (yoke package) being joinedtogether in the first manufacturing step.

FIG. 4 shows the stator unit 14 which is produced in the thirdmanufacturing step 22 on the left side and which has both the stainlesssteel coating 16 and also the wound star-shaped package 4. The rotorunit 15 is shown on the right side of FIG. 4, which essentially includesthe bearings 6, the shaft 8, the magnet 7 and the rotor laminated core9.

Furthermore, FIG. 4 shows the second bearing shield 11, which has thestainless steel coating 17 as already shown in conjunction with FIG. 1.

FIG. 4 illustrates that, in a fourth manufacturing step 23, the rotorunit is introduced into the stator unit 14 and the motor or the electricmachine 1 is completed accordingly by positioning the second bearingshield 11.

The advantages of the motor shown in FIGS. 1 to 4 are, in particular,the avoidance of axial connecting points, into which seals wouldotherwise have to be integrated. In addition, this improves axial heatconduction. Overall, standard components can be used, which are merelycoated with stainless steel so that additional components and additionalcosts can be avoided. Force-fit joints are established by means of theadditive process for stainless steel coating so that additional screwedconnections can be dispensed with, for instance. Furthermore, additivemanufacturing allows for a flexibility with respect to installationlength and diameter without resulting in further tool costs. Storagecosts for different housing dimensions are thus also avoided.Furthermore, on account of the stainless steel coating, the possibilityto respond very flexibly to customer requirements and differingenvironmental conditions is created as a result of modifying thestainless steel.

In summary, the invention thus relates to a housing unit 5 for anelectric machine 1, in particular for a PM servomotor, with a firstbearing shield 10, with an intermediate flange 12 and with a firststator laminated core 3.

A thin-walled stainless steel housing of the electric machine can beeasily and cost-effectively achieved in that the first bearing shield10, the stator laminated core 3 and the flange 12 have a sharedstainless steel coating 16, which is generated by means of an additivemanufacturing method, wherein the housing unit 5 is formed from thefirst bearing shield 10, the stator laminated core 3, the flange 12 andthe shared stainless steel coating 16.

While the invention has been illustrated and described in connectionwith currently preferred embodiments shown and described in detail, itis not intended to be limited to the details shown since variousmodifications and structural changes may be made without departing inany way from the spirit and scope of the present invention. Theembodiments were chosen and described in order to explain the principlesof the invention and practical application to thereby enable a personskilled in the art to best utilize the invention and various embodimentswith various modifications as are suited to the particular usecontemplated.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims and includes equivalents of theelements recited therein:
 1. A housing, comprising a first housing unitmade of aluminum and/or iron metal and forming a unitary structurecomposed of a first bearing shield; a flange; a stator laminated corearranged between the first bearing shield and the flange; and a commoncoating made of stainless steel particles which are applied by anadditive manufacturing method and metal-adhesively bonded to the unitarystructure over its entire outer surface so as to contiguously cover thefirst bearing shield, the stator laminated core, and the flange.
 2. Thehousing of claim 1, wherein the first housing unit is configured toreceive a rotor laminated core having magnets arranged thereon andinteracting with a shaft made from stainless steel and supported inbearings.
 3. The housing of claim 1, wherein the first housing unit isconfigured to receive a rotor unit which includes a shaft made fromstainless steel, a laminated core having arranged thereon magnets andbearings for support of the shaft.
 4. The housing of claim 1, furthercomprising a second housing unit, said second housing unit including abearing shield and a coating made of stainless steel and applied by theadditive manufacturing method and metal-adhesively bonded to the bearingshield so as to cover the bearing shield of the second housing unit,said first housing unit being configured to connect to the secondhousing unit.
 5. The housing of claim 1, wherein the coating has athickness in a range of 1 to 3 mm.
 6. An electric machine, comprising afirst housing unit made of aluminum and/or iron metal and forming aunitary structure composed of a first bearing shield, a flange, a statorlaminated core arranged between the first bearing shield and the flange,and a common coating made of stainless steel particles which are appliedby an additive manufacturing method and metal-adhesively bonded to theunitary structure over its entire outer surface so as to contiguouslycover the first bearing shield, the stator laminated core, and theflange.
 7. The electric machine of claim 6, constructed as a PM(permanent magnet) servomotor.
 8. The electric machine of claim 6,further comprising a rotor unit including a rotor laminated core havingmagnets arranged thereon and interacting with a shaft made fromstainless steel and supported in bearings, said first housing unit beingconfigured to receive the rotor unit.
 9. The electric machine of claim6, further comprising a second housing unit, said second housing unitincluding a bearing shield and a coating made of stainless steel andapplied by the additive manufacturing method and metal-adhesively bondedto the bearing shield so as to cover the bearing shield of the secondhousing unit, said first housing unit being configured to connect to thesecond housing unit.
 10. A method for producing an electric machine,comprising: joining in a first manufacturing step a first bearingshield, an outer laminated core, and a flange to form a first housingunit made of aluminum and/or iron metal; and coating by using anadditive manufacturing method the first bearing shield, the outerlaminated core, and the flange with a common coating made of stainlesssteel particles such that the stainless steel particles in the coatingform a metal adhesive bond with and contiguously cover an entire outersurface of the first bearing shield, the flange, and the outer laminatedcore to establish a first unitary housing structure.
 11. The method ofclaim 10, further comprising Inserting a wound stator laminated coreinto the unitary housing structure.
 12. The method of claim 11, furthercomprising inserting a rotor unit comprised of a shaft, bearings, arotor laminated core and magnets into the housing structure to produce amotor unit.
 13. The method of claim 12, further comprising fastening asecond bearing shield to the motor unit.
 14. The method of claim 12,further comprising smoothing the housing unit and/or the motor unit by ametal cutting process and/or by an electropolishing method.
 15. Themethod of claim 10, further comprising: applying a coating made ofstainless steel by the additive manufacturing method andmetal-adhesively bonding upon a second bearing shield such as to coverthe second bearing shield and thereby form a second housing structure;and connecting the first housing structure to the second housing unitstructure.
 16. The method of claim 15, further comprising forming by theadditive manufacturing method a cooling duct for heat discharge in thehousing structure in a region of the stainless steel coating of thefirst housing structure and/or the stainless steel coating of the secondhousing structure.